When experimenting with my Cometa Orion .22, which is quite loud out of the box @ + 800 FPS, swapping out the hammer spring to something lighter took the velocity way down and made for a pretty quiet and inexpensive bolt action rifle. Once done, there is an external adjustment screw which allows for some flexibility in terms of noise and power without pulling the rifle apart again for further modification. I suspect the same would hold true for my Benjamin Marauder which could be run both PCP HPA or Bulk Fill CO2. The Marauder is a popular, highly adjustable, well documented dual gas bolt action rifle as well. If you are contemplating purchasing one of these new, it might be wise to act soon as the RCMP have recently added this model to the list of airguns which can no longer be imported into Canada. Not sure if anyone has ever tabulated the SPL of non-Moderated airguns in Canada, but my guess is it's all going to boil down to power, volume of compressed air or gas behind the pellet and barrel length. Stands to reason noise level will be directly related to how much HPA or CO2 exits the barrel. I believe one will get higher velocities with lower pressure from a longer barrel than short, which may also lend itself to a quieter report. There are a number of very knowledgeable members on the forum like rsterne who may be able to assist you further.

Cheers,

Avianmanor

I also would reccomend the Artemis 495 fps pcp in 22 or 177 rifle for quiet and great value, though it might seem self serving, since I sell them. I haven't seen anything quieter, and the 177 gets like 150 shots per fill, even without a regulator.
To me, these are the best buy for a low power pcp a guy can get, but I'm biased of course! =)

Sent from my EML-L09 using Tapatalk

If you are looking for >500 fps, non-PAL CO2 bolt action air rifles, I would forward two suggestions.

An Artemis CR600W in .22 cal. Has a 7 shot rotary mag.

Or the Mosin Nagant M1944. A nice BB bolt action. Very close replica of a real bolt action military rifle. Has 16 shot mag.

Both are nice plinkers and are fairly accurate (at least up to 35 ft.).

The Mosin has nice weight to it and has the feel of the real firearm.

I have both, and use them regularly. I would recommend both.

There are other bolt action air rifles like the QB78, which are single shot bolt action.

Thanks Wesb2007 ,
I did get one yesterday ...mine is very loud I got the wrong one, dam. It's the pal .22cal version. maybe shoots 500fps with a 14gr. I did also get the QB78 .177cal .... it's super quiet ! But a real downer in the pellet fiddling dept. I screwed up again. that's 2 rifles I made a mistake. I took about a hundred shots but I realized I can't stand the focus , fiddling takes away from serious shooting. I know better than this. Even in the .22cal shot tray on my Artemis is not a good option at all. I should of gotten the AA400 .177cal 12fpe at least the loading would be fast.
Cheers,
Italo

Thanks Wesb2007 ,
I did get one yesterday ...mine is very loud I got the wrong one, dam. It's the pal .22cal version. maybe shoots 500fps with a 14gr. I did also get the QB78 .177cal .... it's super quiet ! But a real downer in the pellet fiddling dept. I screwed up again. that's 2 rifles I made a mistake. I took about a hundred shots but I realized I can't stand the focus , fiddling takes away from serious shooting. I know better than this. Even in the .22cal shot tray on my Artemis is not a good option at all. I should of gotten the AA400 .177cal 12fpe at least the loading would be fast.
Cheers,
Italo

Cr600w "loud"? , anyhow very easy to tune them down with a hammer spring trim and /Or swap out to a smaller transfer port(available on Ebay) my cr600w is very quiet it has 2.3mm transfer port fyi.

Or just order from Wes, 7$ shipped. I got a TP that I could open up to whatever size and a hammer spring.